This invention relates to a catheter inserting apparatus and, more particularly, it concerns an improved catheter-needle handling device by which a hollow or tubular needle used for penetration to the interior of a blood vessel may be completely removed to leave only a relatively soft catheter remaining in the blood vessel as a conduit by which fluid may be passed between the blood vessel and an external receptacle.
The use of intravenous systems by which fluids are passed directly between a patient's bloodstream and an external receptacle by flexible tubing is well known in the practice of medicine. Most commonly, such intravenous systems involve a direct and essentially permanent connection of the tubing to a rigid tubular needle having a sharpened point for direct insertion through the patient's flesh and into a blood vessel from or to which fluid is withdrawn or introduced. Where the intravenous system is to be used for an indeterminate period of time, such as during the administration of drugs or nurishment directly into the patient's circulatory system, the needle is taped or otherwise fixed against movement to avoid injury resulting from relative movement between the needle and the portion of the patient's anatomy in which the needle is lodged. The major difficulty with such systems is that obviously, the sharpness of the needle point required for effective venipuncture remains to repuncture the veseel and surrounding tissue to cause not only undesirable local injury in the vincinity of the punctured blood vessel, but often a more serious injury as a result of infiltration of fluids to the tissues surrounding the blood vessel.
To circumvent this basic difficulty, systems are now available which permit withdrawal of the needle from the body following venipuncture to leave only a relatively soft plastic catheter in the blood vessel. Of such systems which are available commercially, the catheter is positioned initially in concentric relation with the needle, either directly within a relatively large diameter needle or on the exterior of the smaller needle as an outer sheath. Where the catheter is initially positioned within the needle, the removal of the needle following the venipuncture is along the length of the catheter. Although complete removal of the needle from the catheter extending to the exterior of the patient's body would appear possible, the provision of enlarged diameter coupling or valving sections along the length of the catheter prevents this in practice. As a result, the needle in such systems is usually withdrawn only partially along the length of the inserted catheter and anchored to the patient's body while it remains surrounding the catheter tube. While the likelihood of direct danger of the patient is reduced substantially, the needle can and often does cause an unwanted restriction of the fluid conduit provided by the catheter and may even puncture the catheter.
In those commercially available systems where the needle is initially positioned within the catheter, the exterior end of the catheter must be open to permit needle withdrawal. In particular, needle withdrawal is effected by a thin wire stylus extending the length of the catheter to facilitate removal by pulling the stylus from the exterior end of the catheter. Such an arrangement is undesirable from the standpoint of contamination inasmuch as a direct channel exists for an unwanted period of time between the outside environment and the patient's circulatory system.
Further attempts at catheter insertion or placement systems in which provision is made for needle removal following venipuncture are represented by the disclosures of U.S. Pat. No. 3,399,674 issued Sept. 3, 1968 to K. A. Panier et al and U.S. Pat. No. 3,739,778 issued June 19, 1973 to Martin Monestere, Jr. et al. In the Panier et al patent, a relatively short length of small diameter catheter extends from an exterior juncture with a thick walled tube into a slotted exterior needle oriented at an angle with respect to the exterior tube. After venipuncture, the needle is withdrawn to leave only the small diameter catheter within the blood vessel by virtue of the needle slot extending from the initial juncture with the catheter throughout its length to the pointed end thereof. In the Monestere, Jr. et al patent, the needle initially extends through a sheath of catheter material inserted and left remaining within the patient's blood vessel. After withdrawal of the needle following venipuncture, a small diameter catheter is fed through the needle sheath into the blood vessel through a flexible exterior housing joint.
Although the disclosures of both the Panier et al and Monestere, Jr. et al patents represent catheter insertion systems by which complete removal of a venipuncture needle is facilitated after the catheter placement, neither disclosure takes into account the need for a positive guiding or tracking of the catheter after removal of the needle. It is often necessary, for example, to advance a small diameter catheter along a blood vessel for a length considerably in excess of the length of a venipuncture needle. Because of the extremely small diameter of the catheter and the requirement that it be pushed longitudinally at a point spaced from the end extending within the patient's body, any resistance to longitudinal feeding or threading in this manner will result in a collapse unless the catheter is guided along its length in advance of the point at which the pushing force is applied. Also, it will be appreciated that breakage or severence of the catheter portion within the patient's circulatory system must be avoided whether such breakage is as a result of catheter manipulation after venipuncture or during removal of the puncture needle.